<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <link rel="stylesheet" href="bootstrap-3.4.1/css/bootstrap.css">
</head>
<body>
<input class="btn btn-default" type="button" value="点我">
<button class="btn btn-default" type="button">点我</button>

<input class="btn btn-primary" type="submit" value="点我">
<button class="btn btn-primary" type="submit">点我</button>

<a class="btn btn-danger btn-xs">带你玩</a>
<div style="width:300px; border: 1px solid #dddddd;padding: 30px;">
    <h3>用户登录</h3>
    <div>...</div>
    <a class="btn btn-danger btn-xs btn-block">带你玩</a>
</div>
</body>
</html>